It is a management philosophy which aims at eliminating waste from every aspect of manufacturing and its related activities. The term JIT refers to producing only what is needed.
JIT is defined as “A technique for the organization of work-flows, to allow rapid, high quality, flexible production whilst minimizing manufacturing waste and stock levels.” (CIMA official terminology)
There are two aspects to JIT –
Just- in-time production and
Just- in-purchasing.
JIT production is defined as “A system which is driven by demand for finished products, whereby each component on a production line is produced only when needed for the next stage.”
JIT philosophy aims at reducing waste, which is defined by Fujio Cho of Toyota as -
“any thing other than the minimum amount of equipment, materials, parts, space and worker’s time, which are absolutely required to add value to the product.”
Thus waste is any resource used in excess of the minimum amount required to add value to the product.
More specifically JIT seeks to achieve the following goals.
1. Estimation of non-value added activities
2. Zero inventories
3. Batch size of one
4. A 100% on time delivery service
The following are the key features / characteristics of JIT production.
1. The production line is run on a demand pull basis, so that activity of each work station is authorized by the demand of downstream work stations. Thus, parts move through production system based on end unit demand, focusing on maintaining a constant flow of parts rather than batches of WIP.
2. Set-up time and manufacturing lead time are minimized. Demand-led production may require manufacturing small quantities of the product and producing small batches is economical only if set up time are small.
3. The production line is stopped if parts are absent or defective work